It depends what you want. New Zealand trumps Australia in Natural Beauty, If you’re into more inland tours like visiting glaciers, mud pits, Milford Sound, or the Lord of the Rings tour. If you go to New Zealand it’s a must that you go and watch a rugby match and visit the Cadbury chocolate factory in Dunedin.

Australia has the better beaches and has the great barrier reef which is a must see! Australia has the more interesting animals (see Koalas, Kangaroos, Emus) so a trip to a local zoo is encouraged. Plus the rock made famous by Oprah (Ayres Rock).

It also depends on what Contiki offers and when, either way you can’t lose :)